Fresh meat products are typically processed to various cuts, at a meat processing facility, and then packaged in atmospheric conditions and shipped directly to the supermarket or retail market. Typically, the meat is packaged at the retail market in the Styrofoam trays which are overwrapped with a clear plastic film. Attempts have also been made to package the individual meat products at the processing facility in overwrapped Styrofoam trays, which are then placed within a vacuum-packed barrier bag. The shelf life of such packaging method is relatively short, which is primarily due to the prolonged exposure of the meat product to the residual oxygen present in the packaging. The prolonged exposure to oxygen also causes bacterial decay and discoloration of the meat product.
Particularly in red meat, the prolonged exposure to oxygen causes the conversion of myoglobin meat pigmentation to the grey or brown metmyoglobin, which is unacceptable to the customer. A controlled exposure to oxygen is necessary to oxygenate the meat pigment to a bright red color which, in general, retail customers associate with freshness.
To prevent discoloration and extend the shelf life of meat products, modified atmosphere packaging technologies are used. For example, U.S. Pat. Nos. 5,667,827 and 5,711,978 to Breen et al., disclose a package and method for packaging fresh meat in a substantially oxygen-free atmosphere, which includes a tray that is ventilated with holes and slits and sized to receive a piece of meat. A clear plastic wrapping material covers the tray. A number of these trays are then placed within an outer barrier bag which is evacuated and flushed with carbon dioxide and then sealed. The outer barrier bag is removed when the meat trays are ready for retail case-ready display.
One problem with this system is that it requires use of a perforated tray which may allow bacteria to enter the meat product while displayed. In addition, the packaging process requires the cumbersome grouping and packaging of a number of trays in an outer barrier bag, which then must be evacuated and flushed.
It would be desirable to have a package and process that would avoid the above problems and provide a package which would extend the storage life of meat products. In addition, it would be desirable to have an easy and efficient method for sealing a modified atmosphere tray. Moreover, it would be desirable to have a safe and efficient means of changing the atmosphere within the tray for retail display of the meat product.